SUMMARY: Multiphoton Imaging Core The goal of the Multiphoton Imaging Core (MPI Core) is to provide NINDS-supported Primary Center Investigators, and other neuroscientists at JHU who perform research consistent with the mission of NINDS, access to advanced imaging technology and training to further their ongoing research programs. In particular, the MPI Core will help investigators analyze protein localization, protein dynamics, and protein-protein interactions with high temporal and spatial resolution in situ and in vivo; perform in vivo time-lapse imaging of multiple fluorophores to monitor cell dynamics; combine imaging of ion indicator dyes/proteins with physiological monitoring of electrical activity to assess cellular communication; obtain quantitative information about neuronal morphologies in situ in health and disease to define cell identity and cellular networks; and enable neuronal and glial activity to be monitored in freely moving rodents. This Center grant will provide funds necessary to support two full-time technicians who will manage day-to-day Core activities, provide training and assist in data collection and analysis. It will also support service contracts to maintain Core equipment, and funds to purchase supplies and additional microscope components (e.g. objectives, stages) to adapt existing instrumentation to the needs of its users. In the next funding period, we will substantially expand the capabilities of the MPI Core, by providing access to fiber optic imaging platforms that enable fluorescence imaging in awake, freely moving rodents, by adapting the custom two photon microscope for resonant scanning to enable rapid collection of 3D datasets and reduce motion artifacts, and by establishing a brain clearing and light sheet imaging service to define cell distribution and morphology in the intact CNS. These additional capabilities will allow Core users access to the most recent technology for observing cell structure and cellular activity to determine how these features influence normal behavior and neurological disease. The unique capabilities of the MPI Core will continue to serve as a crucial resource for NINDS-funded investigators at JHU by extending the research capabilities of individual investigators and by serving as a focal point for dissemination and practical training in advanced microscopic methods. Through these efforts, the MPI Core will help establish new strategies for studying brain function in health and disease that will benefit the broader neuroscience community.